Pyruvate kinase

How the Test is Performed:
Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding .

In the laboratory white blood cells are removed, since they can alter test results, and the level of pyruvate kinase is analyzed.

How to Prepare:
If your child is to have this test performed it may be helpful to explain how the test will feel, and even practice or demonstrate on a doll. The more familiar your child is with what will happen to them, and the purpose for the procedure, the less anxiety they will feel.

How it Feels:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing .

Risks:
Risks associated with venipuncture are slight:
  • excessive bleeding
  • fainting or feeling lightheaded
  • hematoma (blood accumulating under the skin)
  • infection (a slight risk any time the skin is broken)
  • multiple punctures to locate veins



Why this Test is Performed:
Hemolytic anemia has many causes, including congenital and acquired. A deficiency in pyruvate kinase is fairly rare, and this test helps your health care provider differentiate the cause of your anemia .

Normal Values:
Pyruvate kinase level results can range from 2 to 8.8 U/g of hemoglobin .

Note: U/g of hemoglobin = units per gram of hemoglobin

Abnormal Results:
Low levels of pyruvate kinase confirm pyruvate kinase deficiency. Your health care provider can also distinguish between anemia caused by pyruvate kinase deficiency and other inherited disorders.

Cost:
Information not available.

Special Considerations:
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.